Touch Sensor Bridge Electrode Design for Parasitic Capacitance Reduction
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Solution Overview
Problem
Existing touch sensors face issues with parasitic capacitance and visibility due to connecting patterns, which degrade sensitivity and image quality in display devices.
Innovation Solution
A touch sensor design featuring a bridge electrode with an extension portion and expanded portions, along with etched regions in the connecting portion, reduces parasitic capacitance and visibility by minimizing overlapping areas and using transparent conductive oxides, thereby enhancing optical and electrical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connecting patterns are used to connect sensing electrodes, then electrical connectivity is improved, but parasitic capacitance increases and sensitivity degrades
Solution Approach 1:
The connecting pattern is segmented into multiple separate lines instead of a single continuous pattern. This segmentation reduces the overlapping area between connecting patterns and sensing electrodes, thereby minimizing parasitic capacitance while maintaining electrical connectivity through multiple discrete connection points
Solution Approach 2:
The harmful overlapping region between connecting patterns and sensing electrodes is extracted and removed by positioning the connecting patterns to avoid intersection with sensing electrode regions. This extraction eliminates the source of parasitic capacitance while preserving the necessary electrical connection function
2Reliability
If connecting patterns are used to connect sensing electrodes, then electrical connectivity is improved, but visibility of electrodes increases and image quality deteriorates
Solution Approach 1:
The connecting pattern is divided into multiple thin, discrete lines distributed across the electrode regions. This segmentation distributes the visibility impact across multiple locations rather than concentrating it in a single continuous pattern, making the electrode structure less visually prominent while maintaining connectivity
Solution Approach 2:
The connecting patterns are designed with different local characteristics - thin lines in regions where they need to be least visible, and strategic positioning to avoid overlapping with sensing electrode areas. This local optimization minimizes both parasitic capacitance and visual prominence while ensuring electrical connectivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively suppresses parasitic capacitance and visibility issues, improving touch sensitivity and image quality by reducing reflectivity differences and preventing electrode visibility.
Implementation Method 1
When the connecting patterns overlap each other, a parasitic capacitance may be generated to degrade sensitivity of the sensing electrodes
Implementation Method 2
using transparent conductive oxides, thereby enhancing optical and electrical reliability
Data Source
AI summary
A touch sensor includes a base layer, sensing electrodes arranged on the base layer, a bridge electrode and a connecting portion. The sensing electrode layer includes first sensing electrodes arranged along a first direction parallel to a top surface of the base layer, and second sensing electrodes arranged along a second direction parallel to the top surface of the base layer. The bridge electrode is disposed on the sensing electrodes to electrically connect the first sensing electrodes neighboring in the first direction to each other. The bridge electrode includes an extension portion and expanded portions formed both ends of the extension portion. The expanded portion has a width greater than that of the extension portion. The connecting portion electrically connects the second sensing electrodes neighboring in the second direction and includes at least one etched region.